Hydrogen sulfide resistant ESP cable

Abstract

An electrical cable for a submersible well pump is provided which is resistant to attack by hydrogen sulfide and which is less susceptible to damage from expanding gases during decompression. The electrical cable has a central copper conductor core. The conductor core is surrounded by a layer of electrical insulation material of either thermosetting or thermoplastic material. Surrounding the insulation material is a polymeric, low permeable layer having a hydrogen sulfide permeability rate which is substantially lower than the insulation material. A metal tape layer, such as lead tape, surrounds the low permeable layer. One or more conductor cores together with the insulation, low permeable layer and metal tape layer can be embedded in an elastomeric jacket and provided with an outer metal armor to provide a single electrical cable.

We claim: 
     
       1. An electrical cable for use in oil and gas wells containing hydrogen sulfide gas, comprising in combination: a copper conductor core;   an electrical insulation layer surrounding the conductor core;   a first layer surrounding the insulation;   a second layer surrounding the first layer, one of the first and second layers being a polymeric, low permeable layer having a hydrogen sulfide permeability rate which is substantially lower than that of the insulation layer, and the other of the first and second layers being a metallic tape layer; and   an outer armor layer surrounding the second layer.   
     
     
       2. The electrical cable of claim 1, wherein: the first layer is the low permeable layer; and   the second layer is the metallic tape layer.   
     
     
       3. The electrical cable of claim 1, wherein: the low permeable layer is a fluorocarbon polymer.   
     
     
       4. The electrical cable of claim 1, further comprising: an elastomeric jacket surrounding the second layer; and wherein   the outer armor layer surrounds the elastomeric jacket.   
     
     
       5. The electrical cable of claim 1, wherein: the metallic tape layer is formed from lead.   
     
     
       6. An electrical cable for use in oil and gas wells containing hydrogen sulfide gas, comprising in combination: a copper conductor core;   an electrical insulation layer surrounding the conductor core;   a polymeric, low permeable layer surrounding the insulation layer, the low permeable layer having a hydrogen sulfide permeability rate which is substantially lower than that of the insulation layer;   a metal tape layer of corrosion resistant metal surrounding the low permeable layer; and   an outer metal armor layer surrounding the metal tape layer.   
     
     
       7. The electrical cable of claim 6, wherein: the low permeable layer is formed from an extruded fluorocarbon polymer.   
     
     
       8. The electrical cable of claim 6, wherein: the metal tape layer is formed from lead.   
     
     
       9. The electrical cable of claim 6, wherein: the low permeable layer is formed by wrapping a fluorocarbon polymer tape around the insulation layer and heating the fluorocarbon polymer tape so that the fluorocarbon polymer tape is fused together.   
     
     
       10. The electrical cable of claim 6, further comprising: an elastomeric jacket surrounding the metal tape layer; and wherein   the outer metal armor layer surrounds the elastomeric jacket.   
     
     
       11. An electrical cable for use in oil and gas wells containing hydrogen sulfide gas, comprising in combination: a copper conductor core;   an electrical insulation layer surrounding the conductor core;   a low permeable layer of a fluorocarbon polymer surrounding the insulation layer, the low permeable layer having a hydrogen sulfide permeability rate which is substantially lower than that of the insulation layer;   a lead tape layer surrounding the low permeable layer, the lead tape layer having interstices to allow passage of gas therethrough;   an elastomeric jacket surrounding the lead tape layer; and   an outer metal armor layer surrounding the elastomeric jacket.   
     
     
       12. The electrical cable of claim 11, wherein: the insulation layer is a thermoplastic material.   
     
     
       13. The electrical cable of claim 11, wherein: the insulation layer is a thermosetting material.   
     
     
       14. The electrical cable of claim 11, wherein: the low permeable layer is formed by wrapping fluorocarbon polymer tape around the insulation layer and heating the tape so that the tape is fused together.   
     
     
       15. A method of forming an electrical cable for use in oil and gas wells containing hydrogen sulfide gas, the method comprising the steps of: providing a copper conductor core;   surrounding the copper conductor core with electrical insulation material;   surrounding the insulation material with a first layer;   surrounding the first layer with a second layer, one of the layers being a polymeric, low permeable layer having a hydrogen sulfide permeability rate which is substantially lower than that of the insulation layer, and the other of the layers being a metallic tape layer having interstices to allow passage of gas therethrough; and   surrounding the second layer with an outer armor layer.   
     
     
       16. The method of claim 15, wherein: the first layer is the low permeable layer; and   the second layer is the metallic tape layer.   
     
     
       17. The method of claim 15, wherein: the low permeable layer is a fluorocarbon polymer.   
     
     
       18. The method of claim 16, wherein: the step of surrounding the insulation material includes wrapping a polymeric, low permeable tape around the insulation layer and heating the tape so that the tape is fused together.   
     
     
       19. The method of claim 15, wherein: the step of surrounding the second layer with an outer armor layer includes providing an elastomeric jacket over the second layer; and   surrounding the elastomeric jacket with the outer armor layer.